Spring type clutch



1952 T. R. SMITH 2,582,077

SPRING TYPE CLUTCH Filed Oct. 27, 1948 g SHEETS-SHEET 1 1952' T. R. 5mm 2,582,077

SPRING TYPE CLUTCH File d Oct. 27, 1948 2 SHEETS-SHEET 2 4 76 /0Z'\ A 30 4% 4 x .92 5 6,57 v 56 62 a Z9 5.5 I I 6 56 34 fig IN V EN TOR.

Tho/72w]? 502L272,

Patented Jan. 8, 1952 -WI G .IYYPE .cturen :Thomasxk, shim-newton, lewa assi norxto 1m.

Marta: .tNe Qat-Iomsa c rporation of elaware Application ombeezr, 1948, s same-55,346

invention relates to. friction clutches and more particularly to friction clutches which are essentially independent .of normal variations in coefficient of friction and operate to transmit a constant torque iii-a me:

The present determined amount from adriving member toe driven member but which permit-slippage be tween .these members when the torque. exceeds such predetermined amount.

Among the objects of the presentylmientionris to provide a constant torqueslip=clutchof'simp1e construction which in onedirection of rotation-of. a driving member effects a frictional drive. between said drive member and .a driven member for transmitting torque in ,a predetermined amount, but which permits slippage between the, members when the torqueexeeeds such "predetermined amount and which at thesame-t.i le:pro-v vides a non-slip driving connection between said, members upon rotation of said dr venmembern the opposite direction.

In many power transmitting assemblies, ,the capacity required of an electricmotor E150 fiause rotation at normal operating speeds ofsomeiinstrumentality driven thereby is lessthanisheefisary to bring said instrumentalityup gtozspeed from rest within relatively short periods: time. In such instances, theinitial'load-placed. upon the motor would be such as to burnout :the field windings of the motor :unless some provision made to control the load whereby the mot-ores not overloaded during the time when the load is. initially applied to. said moton From ,an, 1economical standpoint, it-is more desirable to pro vide a motor of a capacity sufiicient to operate the instrumentality at normal operating speeds of rotation and to provide some means "to prevent; overloading of the motor during theinitial-start: ing operation, otherwise -alarger'motor would be necessary to carry the'loadplaced upon itduring the initial starting operation. Such means may take the form of a clutch mechanism adaptedatc. permit slippage between the motor and the in.- strumentality during the initial starting .'opera,-.- tion to protect the motor against being over;

loaded, the said clutch mechanism gbeing so der signed as to eliminate the slippage after the :instrumentality has beenbrought up:to.n'ormal operating speeds, whereby the motor iscapable of operating under non-slip conditions to=-maintain this normal operatingspeed. Clutches of this type are particularly adapted for use in washing machines in which a basket or receptacle is brought up to speed for spimiingthebasket to remove liquid from thepmaterial-containedtheresuch devices, a motor of relatively small capacity may 'be used to bring the, basket from rest up to operating speed within a reasonable length of time, by providing a friction clutch of theltype herein contemplated between the motor and basket to. prevent overloading of the motor during that period of time, after which the motor operates to spin the basket at normal; Qpere sti speed without slipp ge the. clutch mechanism. i

'Itis', therefo e, an bject of the. n ntion t provide .novel clutch mechanisms adapted to be used under the circumstances immediately above enumerated, whereby some instrumentality, such asa. basket or container for a washing machine,

, gather, withits load,..may be broughtun to 91* mail/operating :speeds within a reasonable length of time without. overloadin the driv n m or ut which provides for transmittal of tor u withoutslippage once the normal operatin speed hasrbeenattained.

other objects, features. capabilities and ad! vantages are comprehended by the invention, as will later appear :andas a e. i her ntl p ss s thereby;

Referring tothedrawines;

'Fieurerl. is a vertical cross-secti a .vi of a. constant torque slip clutchmade in accordance with the present invention, the samebeing taken in 'a.-p1ane-represented by li e j iF eur 2 otthe. drawings;

Figure 2 is ahorizontal cross-sectional view ofthe clutch shown in Figure lot the drawings.

andztakenpin the plane represented by line 2-2 of .thatafigure;

Figure'B iiSfl fragmentary bottom plan view of the. clutch shown in-F'ieure 1 of the drawings discl sing certainacliu tim;v mech n sm. m e in tail:

Figure 4 is a vertical cross-sectional view similar to that :of "Figure 1 ,of the drawings disclostaken in the driven member.

ing .a,;modified form of clutch mechanism, and taken more particularly in the plane represented by line 47-4 of Figure 5 of the drawings;

Figure ,5 is a horizontal cross sectional view the plane represented by line 5-5 of Eigure :4 of 'the drawings and Figures is aview'in perspective ofa coil spring used in bothof-the modifications for frictionally transmitting torque from the driving member to Referring-now more in detail to the drawings, an embodiment selected to illustrate the invention is disclosed in Figures 1 to a'drivingmember in the form 3 as comprising of a-pulley'z a amount dependent uponactuating end of the spring 38 by spiral spring driven member 4 and clutch mechanism 6 for transmitting torque between said members. More particularly, the assembly as herein disclosed is especially adapted for use in washing machines in which a drive is effected between a source of power, such as an electric motor or the like,and a basket or container whereby the said basket or container may be-rapidly rotated for extracting liquid from the clothes or other materials contained therein.

The pulley 2 is provided with ripheral groove l adapted to receive a beltdriven by any suitable source of power, such as an electric motor or the like. with a central hub 12 having a bushing or hear-- ing l4 mounted therein which is mquntedfor roj l6 of the driven member 4.

tation about a hub a V-shaped pe- This-pulley '2 is formed The pulley 2 is formedwith a depending cylindrical wall providing an inside cylindrical face 22 through which a friction drive .is effected be-. tween the pulley 2 and the driven member 4. The driven member 4 has its'centralhub l6 :keyed, as at 24, to a shaft 26 driven thereby foroperating any desired instrumentality; The driven member 4 is further characterized by having a disc-shaped body portion 28 extendingradially from the hub is which has a cylindrical wall.3ll extending upwardly therefrom in spaced relation inwardly of the periphery thereof to provide .a shoulder 32, the said'wall being also spaced from the wall 26 of the drivingmember 2. Mounted upon the driven member 4 in embracing relation to the central hub 16 thereof is va washer 33 adapted to form a bearing whereby the pulley 2 andbushing l4 are rotatably supported by the driven member 4. The driving and driven members are maintained inoperative position with respect to the shaft 26 byfmeans of-the spring re tainer ring 34 which is snapped into an annular the end of the shaft 26 groove 36 formed adjacent and disposed in abutting member 4. I

Disposed within the annular space provided between the walls 20 and of the driving and driven members, respectively, is a helically wound spring 38, each turn of which is rectangular in cross-section to provideinner and outer surfaces formed of uniform diameter. This spring .embraces the-wall 30 of the driven member and is supported upon the annular shoulder '32 and has one end thereof, namely its pick-upendMl, disposed in abutting relation as a part of the driven member which'extends above the shoulder 32 thereof. .The'other or driv ing end of the spring 38 is yieldably engaged by the outer end 44 of a spiral spring 46iwhich has its other or inner end 48 secured within the slot 50 of a support 52 which is mounted upon the' driven member 4 radially of the wall 36. The outer end 44 of the spiral spring 46 extends outwardly through an opening 54 provided in the wall 36 into engagee ment with the driving end of the spring 38.- i

As will be clearly apparent, the spring 46 urges the spring 38 into frictional engagement withtha surface 22 of the driving member 2'.whereby a'. frictional drive is effected'between the'driving and driven members 2 and 4, the driving member 2 is rotated in acounterr clockwise direction, as viewed in Figure 2 ofsthedrawings, the clutch spring 38'is effective to transmit torque between the driving and driven, members through the spiral spring 46 in an the iorceap igd to t e;

relation to the driven respectively.

jing surfaces of the driving member'and spring 38 than it takesto actuate the spring 46. There is thus provided a friction clutch mechanism in which constant torque in a predetermined amount can be transmitted in one direction only between the driving and driven members which, if exceeded, permits slippage'between the said members so that it is impossible with such an ararngement to overload the drive motor, or the like. If ;th e; driving member 2 is rotated in a clockwise direction, as viewed in Figure 2 of the drawings, a direct drive is effected between the same and the driven member 4.

In order to adapt the friction clutch mecha nism for the transmittal of torque in varying amounts, the spring. mounting is made adjustable. As will be noted, the support 52 is rotatably mounted within the hub 56 extending upwardly from the body portion 28 of the driven member 4.. The support 52 is provided with a lower flanged end 58 adapted to abut the hub 56 which is formed with peripheral under-cut grooves 66 adapted to be select'vely engaged by one or more modification of to a lug-'42 formed 1 projections extending laterally at the end of a latch member 62 which is secured by means of a bolt 64 to the body portion 26 of the driven member 4. It will be clear from the drawings that the bolt 64 provides means for locking the latch 62 with respect to the support 62 and the latch 62 serves to maintain the support 5?. in its operative association with the hub 56. The spiral spring 46 may be readily adjusted for exerting a variable force to the end of the coil spring 38 by rotating the support 52 and locking said support in any of its adjusted positions by means of the latch 62 and bolt 64.

Figures 4 and 5 of the drawings illustrate a the present invention, the same including a driving member in the form of a pulley 2, conforming to that disclosed in Figure, l of the drawings, the same having a V-shaped peripheral groove ID for receiving a belt which may be driven from a source of power, such as a motor or the like. This pulley 2, as in the previous illustration, is formed with the central hub i2 having a bushing or hearing l4 fixed therein which is mounted for rotation about the hub 66 of a driven member '68. The pulley 2 is also formed with a depending, cylindrical wall 20 having the inner cylindrical friction surface 22, all in accordance with the embodiment shown in Figures 1 and 2 of the drawings.

In this illustrative embodiment of the invention, the driven member 68 and the clutch mechanism 'Ill'varies somewhat from the correspond- Y the purpose of providing for the transmittal of constant torque in a tween the driving and driven members 2 and 68, respectively, in both directions of rotation of the drive member 2 and tweenwhen the torque exceeds said amount.

--.The driven member 68 is keyed to the shaft 26 bykey 24 for driving any desired instrumentality and isprovided with a-disc-shaped body portion- 12 extending outwardly from the hub 66 which has an upstanding, substantially cylindrical wall 14 off-set inwardly and radially from the periphpredetermined amount be-J to permit slippage therebe-;

bers are secured inoperativerelationtothe shaft 2b by means of a spring retainer rin 11 adapted 'to be snapped-into an annular groove 19- formed adjacent the end "of sh'aft'26 and disposed 'in abutting relation to" the driven member 68. Mounted upon the drivenmember 88in embracing relation to the central hub 66 thereof is a washer 8i adapted to form a bearing whereby the pulley 2 and bushing M are rotatably-sup' p'orted by the driven'meniber';

The torque transmitting clutch mechanism embodies a h'elically Wound spring 38', correspondins-to the spring of theembodimentish'own-"in Figures 1 and of the drawings; which embraces the wall 74 of the driven member 68 and is supported. by the annular shoulder 16 "formed thereon. This clutch mechanism further embodies a spiral spring 82 having its'in'ner end 8'4 within the slot 86 formed'l'n the upper mounted surface of a pedestal or boss 88 extending upwardly from the body portion 12 of the driven member. Th other end 90 of the spring 82-extends outwardly through the opening 18 into yieldable engagement with the u per end 92 of the coil spring 38. The clutch mechanism furher embodies a spiral spring 94 conforming substantially to the spiral spring 82 which has its inner end 96 disposed within a slot 98 formed in the boss or pedestal I80 which extends upwardly from the body portion 12. The other-end I92 of the spiral spring 94 extends outwardly through the opening 8din'the'wall 14 lower end I94 of'the spring 38.

It will be apparent that spiral springs '82 and 34 exert a force against the ends of the spring 38 to expand the same into frictional er'iga'gement with the surface 22 of the driving member 2. These opposite forces are constant so that a constant torque of predetermined value may be transmitted between the -'driving and driven members in either'dir'ection of rotation of the driving member and will permit slippage "between these members when the torque exceedss'u'ch predetermined amount. Thus, assumingthe driving member 2 is rotated in a clockwise dire'ctionand that the loading on the driven member 68 exceeds the predetermined loading of the spiral spring 94, the coil spring 38 and the wall 20 "of the driving member moves relative to the driven member and the coil spring 38 will, with the end I04 thereof pushingagainst the end 192 'of'the spiral spring 94, transmit torque therethrough to likewise rotate the driven member 68 in a clockwise direction. The end 90 of the spiral spring 82 maintains the end 92 of "the-coil spring 38 in contact with the drum surface 22 until the end 90 engages the wall or abutment 19 of the opening 78 to thereby stop its m'ovementinthat direction. Upon continued relative movement between the coil spring 38 and the driven member 68, the spiral spring 94 contracts furtherand the end 92 of the spring 38 moves out of contact with the end 90 of spring 82 and the spring3'8 contracts toward the driven drum to permit slippage between it and 'the Wall "29 to limit the torque.

When the rotation of the driving member 2 is in a counterclockwisedirectionand'underexcessive load conditions, the oppo'site action takes place in that the end'92 or coll spring 3B' tra'n's and engages the tails and features I nits the torque to the driven member 68 through the smart of the 'spiralsprin '82 and moves it away from the abutment 19. As the 'coil si'ari'n'gv '38 c'ontin'ues to moverelativeto the'driven member 68,;theend IOZ 'of thespiral spring 94 follows 1 04 of the coil spring to maintain ltjin engagement with the driving drum surface 22.

This continues until-the-end I 02 of spring "'94 engages the wall orabu'tmentss of the-opening whereby, when the spiral spring is moved further by reason of an 'overload,-the end (04 of the coil-spring- 38 moves away from the end [92 and contracts toward the driven drum for the reasons given "above. It is"contemplatedthat inth'eevent it :is desired to varythe tension" of the springs '82 and 94 "of this embodiment, this maybe done: by imcorporating the adjusting means of the first described embodiment therein; It should-be noted thatthe'ends -9fl and 102 of the rspirai spring -82 and 9 1, respectivelygprovide resilient connections or yi'eidable abutments for the ends-of the spring 38 in'contra-distinction to the fixed abutment 42 of the embodiment shownin-Figure 1.

In both embodiments, the friction drive between the drivingand .driven'memb'ers builds "up exponentially according to the formula:

where it is a constant, '1 is the coefiicient ofJfriction and is the angular wrap'of the spring'38 around the wall 14 expressed in radians. Accordingly, a friction drive is efiected which-will cause slippage between the driving and driven members at a constant maximum torque. .This drive between these membersis also always effective below this maximum torque. valueregardless of any reasonable variation in the co'efiicient of friction. While I have herein described and upon the drawings shown illustrative embodiments of the invention, it is to be understood that the :invention is not limited thereto, but may comprehend other constructions, arrangements of parts, de-

without departing from the spirit of the invention. I

It is claimed:-

1. A friction clutch comprising a driving meme her and a driven member, 'and'm'eans providing for the transmittal of'a constant torque in a pre--- determined amount from said driving to said driven member and permitting slippage between members when the torque exceeds said amount, said means including a coil spring clutch element carriedby'one of said members and frictionally engaging the other of said members, means providing a connection between said one of said members and one end of said clutch-element,- a spiral spring connected at one end to said one of said members and having its other end operatively connected at the other end of said clutch element for applying a force tomove said clutch element into frictional engagement'with the other of said memberaand means for adjusting the connection between said spiral spring and said one of said members for varying the'force applied by said spiral sprin'g'to said clutch element.

2. A friction clutch comprising a drivingmemher and a driven member, and means providing for. the transmittal determined amount from said driving to said driven member and permitting slippage between said members when the torque exceeds said amount when said driven member is rotated in one direction and to provide 'a positive driving of a constant torque in a prespring having one end 'one of said members and element carried by one of said members and frictionally engaging the other of said members, an

abutment on said one of said members engageable with one end of'saidclutch element, a spiral thereof connected to said in engagement with the other end of said clutch element for applying a force to move said clutch element into frictional engagement with the other of'said members, and means for adjusting theconnection between said spiral spring and said one of said members for varying the force applied by said spiral spring to said clutch element.

3. A friction clutch comprising a driving member and a driven member having concentrically disposed cylindrical walls radially spaced with respect to one another, and means providing for the transmittal of constant torque in a predetermined amount from said driving to said driven member and permitting said means including a coil spring clutch element carried by said driven member and disposed within the space between said walls, abutment means carried by said driven member engageable with one end of said clutch element, and yieldable means mounted on said driven member inwardly of the cylindrical wall thereof and extending through an opening therein into engagement with the other end of said clutch element for applying a force .to expand the same into frictional engagement with said driving member.

, 4. A friction clutch comprising a driving member and a'driven member having concentrically disposed cylindrical walls radially spaced with respect to one another; and means providing for the transmittal of constant torque in a predetermined amount from said driving to said driven member and permitting slippage between said members when the torque exceeds said amount, said means including a coil spring clutch element carried by said driven member and disposed within the space between said walls, abutment means carried by saiddriven member engageable with one end of said clutch element, and a spiral spring having one end connected to said driven member inwardly of the cylindrical wall thereof and having its other end extending through an opening therein into engagement with the other end of said clutch element for applying a force to expand the same into frictional engagement with said driving member.

5. A friction clutch comprising a driving member and a driven member having concentrically disposed cylindrical walls radially spaced with respect to one another, and means providing for the transmittal of constant torque in a predetermined amount from said driving to said driven member and permitting slippage between said members when the torque exceeds said amount. said means including a coil spring clutch element carriedby said driven member and disposed with in the spacebetween said walls, abutment means carried by said driven member engageable. with one end of said clutch element, a rotatably adjustable support mounted in said driven member, and a spiral spring having one end connected to said adjustablesupport and its other end extending through an opening in the wall of said driven m intgr eaeem n Wi v1 'otherie cl 1 said clutch element for applying a force to exslippage between said members when the torque exceeds said amount,

having its other end tween said members when ahead? pand the same into frictional engagement with said driving member.

6. A friction clutch comprising a driving member and a driven member, and means providing for thetransmittal of a constant torque in a predetermined amount from said driving to said driven member in either direction of rotation of said driving member and permitting slippage bethe torque exceeds said amount, said, means including a coil spring clutch element carried by one of said members and frictionally engaging the other of said members, and spiralsprings each having one end connected to said one of said members and the other end in engaging relation to an end of said clutch element for applying a force at each end of said clutch element to move the same into frictional engagement with the other of said members. 5.

'7. A friction clutch as defined in claim 6 in which means is provided for adjusting the connection between said spiral springs and said one of said members for varying the force applied by said spiral springs-to said clutch element.

8. Arfriction clutch comprising a driving member and a driven member having concentrically disposed cylindrical walls radially spaced with respect to one another, and meansprviding for the transmittal of a constant torque in a predetermined amount from said driving to said driven member in either direction of rotation of said driving member and permitting slippage between said members when the torque exceeds said amount, said means including a coil spring clutch element carried by said driven member and disposed within the space between said walls, yieldable means mounted on said driven member and extending through openings in the wall thereof into engagement with the ends of said clutch element for applying a force at each end of said clutch element to expand the same into frictional engagement with said driving member.

9. A friction clutch comprising a driving member and a driven member having concentrically disposed cylindrical walls radially spaced with respect to one another, and means providing for the transmittal of a constant torque in a predetermined amount from said driving to said driven member in either direction of rotation of said driving member and permitting slippage between said members when the torque exceeds said amount, and means including a coil spring clutch element carried by said driven member and disposed within the space between said walls, spiral springs each having an end connected to said driven member and an end extending through an opening in the wall of said driven member into engagement with an end of said clutch element for. V applying a force to expand the same into -frictional engagement with said driving member.

10. A friction clutch comprising a driving member and a driven member having concentrically disposed cylindrical walls radially spaced with respect to one another, and means providing for the transmittal of a constant torque in a predetermined amount from said driving to said driven member in either direction of rotation of-said driving member and: permitting slippage between said members when the torque exceeds said amount, said means including a coil spring clutch element carried by said driven member and disposed within the space between said walls, rotatable adjustable supports :mounted in said driven member, and spiral springs each having an end connected ,to an adjustable. support, and an end extending through an opening in the wall of said tween said members when driven member into engagement with an end of said clutch element for applying a force to expand the same into frictional engagement with said driving member.

11. A friction clutch comprising a driving member and a driven member, and means providing for the transmittal of a constant torque in a predetermined amount from said driving to said driven member in either direction of rotation of said driving member and permitting slippage bethe torque exceeds said amount, said means including a coil spring clutch element carried by one of said members and frictionally engaging the other of said members, springs each having one end connected to one of said members and the other end in engaging relation to an end of said clutch element for applying a force at each end of said clutch element to move the same into frictional engagement with the other of said members, and abutments for limiting the angular movement of said last mentioned springs during overload conditions to permit said coil spring clutch element to release.

12. A friction clutch comprising a driving member and a driven member having concentrically disposed cylindrical walls radially spaced with respect to one another, and means providing for the transmittal of a constant torque in a predetermined amount from said driving to said driven member in either direction of rotation of said driving member and permitting slippage between said members when the torque exceeds said amount, said means including a coil spring element carried by said driven member and disposed within the space between said walls, and yieldable means mounted on said driven member and extending through openings in the wall thereof into engagement with the ends of said clutch element for applying a force at each end of said clutch element to expand the same into frictional engagement with said driving member, said wall providing abutments to limit the relative angular movement of said yieldable means to permit said coil spring and yieldable means to disengage to thereby limit the torque transmitted through said spring clutch.

THOMAS R. SMITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

